Gavin Robinson has retained the Belfast East seat for the DUP.
Mr Robinson received 23,917 votes, well ahead of Alliance leader Naomi Long, who received 15,443.
He pledged to be a strong voice for his constituency in Westminster as the UK leaves the European Union.
"Our focus has always been on getting the best deal for Northern Ireland in terms of leaving the European Union.
“The national picture is pretty unclear at this moment in time.
"If there is an opportunity for us as a strong voice for Northern Ireland to play a key and significant role in the future of government in the United Kingdom and getting the best deal for Northern Ireland on a whole host of issues, then we will be in a good place to do that."
Surge in votes
Naomi Long said the Alliance vote held up well, but across Northern Ireland there had been a surge of unionist votes as a reaction to Sinn Féin doing so well at the Assembly election in March.
“In East Belfast, we have added a few thousand votes from the Assembly election only a matter of weeks ago but the DUP have added more.
"The Ulster Unionist vote has entirely collapsed and I think we are seeing that repeated right round Northern Ireland.
“The Ulster Unionists collapsing to the DUP, the SDLP collapsing to Sinn Féin.”
Ms Long said the hugely polarised election had become “a headcount”.
“That does not bode well for the restoration of our institutions,” she said. “But we will be there on Monday and we will be ready to work with those who are ready to work with us to find the necessary compromises to ensure that we restore devolution and serve the public who have put their faith in us.”
Previous Westminster elections
2010 – Naomi Long (Alliance) defeated DUP's Peter Robinson (12,839 votes to 11,306).
2015 – Gavin Robinson (DUP) beat Ms Long (19,575 votes to 16,978).
